Bricked nRF52840-dk

[Jerry Easley]

I had a pathological application running of my nRF52840 so I reset/power sequenced it; that procedure got rid of the pathological program but it also broke JLink, I think.  In any case it now connects as a usb serial device.  Apparently I need to reflash it in order to restore functionality,  There are other tickets on here concerning this issue and which I have reviewed.  I found the restorative procedures posited there to be incomprehensible; I am a newcomer to Nordic an I am not at all familiar with the tools used to do this,  So I need instructions in great detail.

Regards,

Jerry

[Simonr]

When using a DK and the USB example projects, you need to use the nRF USB connector (J3) instead of J2 that goes to the Interface MCU. Please check that the nRF USB is connected to the computer, and that the switches on the nRF52840 DK are in the correct position.

• SW9 to the middle position (VDD)
• ¨SW6 to DEFAULT
• SW10 to OFF

Best regards,

Simon

[Jerry Easley]

Hi Simon,

I have SW9 to mid pos (VDD)

I have SW6 to DEFAULT.

If I turn SW10 to OFF I lose all power to the board.  (are you sure it should be off; it is the power switch?)

If I turn SW10 to on, I get the ACM port, but no Jlink ports

This board seems to behave differently every time I touch it.

Yesterday, it would instantiate J-Link ports but would not instantiate ACM ports, today it will instantiate an ACM port but not J-Link ports.

In any case I have and have had the switches set as you direct, except SW10, which I have set to on.

I have both USB ports connected to my PC; my application is running and I can monitor the ACM port via Putty.

VSCODE cannot communicate with it because the J-Link ports are not instantiated.  

I am very confused.

Regards,

Jerry

[Jerry Easley]

Hi Simon,

I am such an idiot; I was confusing SW10 with the power switch. I believe I had SW10 set to the on position.

I have changed it to off. Now the board does not instantiate any virtual com ports at all; completely dysfunctional.  If I move sw10 back to on and try it, it’s still completely dysfunctional. For now I’ll I’ll leave it in the off position as you have directed.

I am now even more confused by this board’s behavior.

Regards,

Jerry 

[Jerry Easley]

I moved the board from my Windows 10 system to Ubuntu and, viola, the ACM port appeared an I can monitor console traffic across it. I then moved it back to windows and  sure enough the ACM port appears an I can monitor console traffic across it.  Still no J-Link ports though.

There is something going on which I don’t understand.

[Jerry Easley]

I have another ticket open about instability in Windows which manifested its self when running a console application.  It now appears that problem was caused by my antivirus software, Avast.  I disabled Avast and the other problem seems to have gone away.  I just plugged my nRF52840-dk in and it now seems to be working correctly. So I suggest we put this issue on hold until I do some further testing. I’ll update you with what I find.

Regards,

Jerry